Thermionic vacuum tube



y 1939- J F, CUDNEY THERMIONIC VACUUM TUBE Filed Feb. 25, 1937 Patented May 9, 1939 :31 TAT- 1.1

PATENT GFFi 5 Claims.

This invention relates to electron discharge devices, in general.

It is known that in the operation of such devices there is prevalent in the magnetic field of the plate anode a variation of the magnetic flux, thereby establishing a greater flux value upon the edges than exist in the region therebetween said edges, the non-uniform distribution of the magnetic field on conductors of various shapes is described by (Ewing) as The lagging of magnetism in a magnetic metal, behind the magnetizing flux upon said edges which produces it.

The aforementioned greater value of the magnetic field flux results in undesirable end capacity 15 effects between the anode and control grid concentric thereto, inter-coupling effects between the anode and other electrically conductive elements exterior to said anode also results from said overcharge cf flux at said ends of anode. Deflection 20 of the electron stream from a rectilinear course to the plate is a further result of said end over-loading of said anode by said flux. The portion of anode wall lying between the ends thereof and having a much lower flux value than the ends contributes to what is termed electron rebound as a result thereof; quenched signal-strength; distortion of the carrier waves also results therefrom and that by reason of the aforementioned undesirable effects the amplifying effect of the 30 device may be greatly reduced.

An object of my invention is to overcome the disadvantages previously referred to and provide a simple inexpensive, but reliable and efficient device of the character described, which may be 35 employed to obtain a superior degree of distribution of the magnetic flux over the area of the plate anode and concentrically to the wall thereof and produce thereby a superior degree of electron con trol between the cathode and anode than heretofore obtained in the prior art.

Another object of my invention is to construct a plate anode provided with means to cause a diversion of part of the field magnetism abounding on the periphery thereof to the inner wall 5 thereby to minimize inter-coupling between electrcde ends and other electrodes in a device by providing an equipotential inner wall surface.

Another object of my invention is to so construct a metal anode having elongated apertures so in the wall thereof and connected by narrow strips and means whereby the width of the said apertures may be set at a given gauge during the stamping operation, in the manufacture of said anode, making it possible to embody more mag- 55 net surface in the anode wall by the means of contraction grooves in the said narrow strips than possible heretofore in an anode of like dimensions, thereby producing a greater magnetic area of uniform characteristics over the inner wall of said anode and requiring no more space than prior devices. 5

Another object of my invention is to provide means in the construction thereof to eliminate electron rebound.

Another object of my invention is to construct a plate anode adapted to rectification of alternating current purposes as well as detection, amplification, and other electron discharge purposes.

Another object of my invention is the construction of a plate anode which will withstand high operating temperatures.

Another object of my invention is to construct a plate anode provided with means whereby faster dissipation of metallic gases from the anode metal be accomplished during flashing of the tube.

A further object of the invention is to provide a plate element which may be accurately and quickly produced.

I have found that if an anode be constructed having elongated apertures in the wall thereof and with shoulders having an inwardly diverted portion of the wall surface forming flanges, to prevent electron passage therethrough said anode wall, and the axial length of said anode contracted by means of grooves so that said flanges may be brought quite close to each other and the width of said apertures in a minimum gauge, thus breaking up the wall into branch portions, that an equality in diffusion of the magnetic flux over the inner area of the anode will result therefrom and that the electron stream will then flow in a direct and symmetric course from the cathode to the plate anode and that said capacity at ends of said anode be eliminated thereby, and that as a result thereof the degree of amplification obtained with a single device may be greatly increased.

Features and advantages of my invention other than those above noted will be apparent from the following description taken in connection with the accompanying drawing in which Figure 1 is a side elevational view partly in section of an evacuated electric device embodying my invention in a preferred form, a portion of the containing walls of the envelope being broken away and the plate anode, cathode and grids shown in longitudinal section.

Figure 2 is a horizontal section on an enlarged scale taken on line 22 of Figure 1.

Figure 3 is a vertical elevational view partly in section taken on line 3-3 of Figure 1.

Figure 4 is a perspective view of my anode.

Figure 5 is a perspective view of a modification of my invention and showing separate annular radially flanged rings secured to upright supporting posts.

Figure 6 is a perspective view of a modification or" my invention showing the complete anode stamped in two sections with lateral extending flanges and adapted to engage supporting posts between said lateral extending flanges and by which the two sections may be secured thereby Weld, or, brazed.

Figure 7 is a perspective View of the complete anode in modified form showing vertical slots in place of the radial slots.

Figure 8-is a perspective view of a modification similar to Figure 7 but showing same in two sections with lateral extending flanges adapted for securing of same to upright support posts.

In a preferred form of embodiment of my invention as shown in Figures 1, 2, 3 and 4 by way of example I provide an elongated envelope 2| having a reentrant portion 23 terminating in a supporting press. As shown the various elements of a discharge tube may include a cathode 34, a control grid 24, a screening grid 33, cathode heater conductors 25, a cathode conductor 26, a bell cap with a lead wire secured therein the other end thereof secured to the control grid as shown at 22, a base 2'! provided with hollow pins (not shown), leading in conductors being secured in the usual manner in said hollow pins, plate anode supports and the means for conducting current to the anode indicated at 3|. Figure 1 at 29 shows a face portion of my invention the apertures between said face portions of the annular ribs, also the U shape of the cross section of the annular ribs being quite apparent, said portions in parallel and constituting the plane of the anode wall, the inwardly diverted radial flange on both edges as shown by numerals 32, 3030 giving the ribs the aforementioned U shape when viewed in cross section as shown by numeral 29. The alternating current traversing the branch members 29 and the radial flanges 32, 3030 Figure 1, and 2, 3, and 4, and crossing the closely apertured radial flanges via induction as well as via direct coupling at the supporting posts produces a distribution of the magnetic flux adjacent the inner anode wall and extending concentrically from said wall plane in accordance with the width of said flanges therefrom. In Figure 2 numeral l9 shows a dielectric strip for supporting and spacing of the electrodes within the anode enclosure said electrodes indicated at 34 cathode, 24 control grid, 33 screening grid, a connecting strip with a post support groove 35 and intersecting the radial ribs with radial flanges thereon. Fig. 4 shows a contraction groove 36 intersecting the support post groove 35 the groove 36 being on a like plane with the annular ribs and a groove at the termination of each elongated aperture whereby means is provided thereby for contracting the elongated apertures to a minimum width thus drawing the annular ribs closer together for the purpose of induction in the alternating current between the annular flanges 3032. Figure 5 shows a modification of the invention providing separate annular rings 31 with radial flanges 3B thereon and secured to supporting posts 39 in parallel and in spaced relationship to each other, Figure 6 shows another modification of my invention whereby the anode may be stamped in two sections 4| showing the radial flanges two of which are situated on each rib and at right angles to the plane of the wall surface 40, 42 shows the two discrete lateral extending flanges having contraction grooves 43 on each half of the anode, each pair opposite and adapted for the securing therebetween, each pair of a support post to hold the two sections and support same. Figure 7 shows another modification of the invention with vertical elongated apertures between the ribs 44, vertical flanges 45 in place of radial flanges, and 41 shows the contraction grooves in the intact wall of the anode and at the junctures of the apertures, 45 indicates a radial flange on the top end of the anode another (not shown) on the bottom edge thereof. Figure 8 shows a modification of my invention similar to Figure 7 with vertical slots between the ribs 49, but stamped in two sections after the manner of Figure 6. Vertical flanges instead of radial flanges are incorporated therein and indicated at 50 with contraction grooves 5| stamped in the intact wall of the anode and crossing the radial flange 49 at the top thereof, another radial flange (not shown) but similar to 49 at the bottom edge of said sections said flanges extending radially from lateral extending flanges 52 to the flange on the opposite side of the sections, a vertical groove (not shown) but similar to 35 Fig. 4 in each flange and upon the portions adjacent each other for securing the sections to support posts (not shown) producing a tighter flt of the parts comprising the plate anode sections.

By the means which I have described said means comprising an equipotential plate anode surface, the properties of the magnetic field having a marked tendency to isolate the region of the anode wall between the said edges thereof to an appreciable degree and produce thereby end capacity effects and exterior interference between the device and other devices employed in a system and distortion of the electron stream, may be so eflectively eliminated as to be entirely unappreciable.

While I have shown and described the preferred form and embodiment of my invention, it will be apparent that many modifications may be made in the structural details employed for carrying my invention into effect without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. A tubular anode for an electron discharge device, said anode being formed of sheet material and being slotted to provide a plurality of substantially parallel bridge formations, the marginal edges of said bridge formations being formed to provide inwardly directed flanges which extend substantially the length of said slots, portions of the wall of said anode connecting said bridge formations, said wall portions being indented to reduce the spacing between the flanges of adjacent bridge formations so as to prevent passage therethrough of electrons.

2. An electron direction control device of tubular form comprising a plurality of trough shaped members spaced adjacent each other in parallel and secured together by means of two integral oppositely disposed webbed tracts transverse to said trough shaped members, an elongated opening betweeneach said member and extending from one to the other of said webbed tracts, portions of said webbed tracts crossing the extremities of said elongated openings, a channel in each said webbed portion substantially on a line with the said elongated openings between each of the said trough shaped members, said trough shaped members also having integral thereto inwardly directed sets of flanges substantially the length of said elongated openings.

3. An electrode for electrical discharge vessels comprising a cylinder formed of conducting bodies spaced apart and connected together in parallel formation, a plurality of inwardly directed flanges integral to said bodies and transverse to said bodies, said connections between said bodies having a thermal expansion compensating groove between each said body.

4. An anode for thermionic vacuum tubes comprising strap members bent to form a tubular enclosure and having the marginal edges thereof 15 turned at an angle to provide a flange for each,

the said flanges arranged within the anode enclosure in parallel formation, and means for connecting all of the said flanged straps together, and a thermal expansion groove intermediate said straps.

5. An arrangement for reducing isolation of electrical lines of force upon the working surface of an anode between the top and bottom ends thereof, comprising sheet material slotted. and having horizontal and longitudinal intact portions intermediate said slots, inwardly directed vanes extending substantially the length of said slots and arranged to prevent passage therebetween of electrons.

JOHN F. CUDNEY. 

